"""Linear referencing
"""

from shapely.topology import Delegating


class LinearRefBase(Delegating):
    def _validate_line(self, ob):
        super(LinearRefBase, self)._validate(ob)
        try:
            assert ob.geom_type in ['LineString', 'MultiLineString']
        except AssertionError:
            raise TypeError("Only linear types support this operation")

class ProjectOp(LinearRefBase):
    def __call__(self, this, other):
        self._validate_line(this)
        self._validate(other)
        return self.fn(this._geom, other._geom)

class InterpolateOp(LinearRefBase):
    def __call__(self, this, distance):
        self._validate_line(this)
        return self.fn(this._geom, distance)


